Thermodynamically-controlled knife switch



MALCOLM H. BAKER, DECD.

MARIE H- BAKER, ADMINISTRATRIX.

THERMODYNAMICALLY CONTROLLED KNIFE SWITCH. APPLICATION FILED OCT. 8.1915. RENEWED APR. 14,1919.

1,407,31 5, Patented Feb. 2], 1922.

UNITED STATES PATENT OFF-ICE.

MALCOLM n. BAKER, or 3mm, mnssacnusn'r'rs; MARIE n; mxnn. ummus-v rnarmxor moon: a BAKER, DECEASED, nssrenon, :sr mnsnn assronnnn'rs, T rumourPRODUCTS COMPANY, A oonronnrron or massacnusnrrs.

Application 'filed October 8, 1915, Serial No. 54,882. Renewed April 14,1919. Serial No. 290,084.

Toall whom it may concern."

Be it known that I, MALCOLM H. BsKER, a citizen of the United States,and a resldent of- Braintree, in the county of Norfolk and Cdmmonwealthof Massachusetts, have invented certain new and useful Improvements inThermodynamically-Controlled Kn fe Switches, of which thefollowing is aspecification 1 Myinvention relates to switches for electric circuitsformed with pivoted or swinging, blades, of the type usually lmown as fknife switches.

The object of my invention is toprovide, in combination with such aswitch, means, under the control of the operater, whereby the saidswitch maybe closed fora contin uous period of time, as required fornormal operation of the controlled circuit, and whereby, when it isdesired to open the switch, an automatically performed opening movementmay be had, operative a predetermined time after the actuation of thecontrolling means of the switch; the preferred arrangement being onewhereby the same controlling member, actuated manually or otherwise,which ispsed to -close the switch is also employed to put into operationthe delayed automatic 0 ening means. 7

In other applicatlons filed by melt have illustrated and broadly claimedsuch retard- .ed automatic switch opening devices as broadly applicableto various well known types of switches for electric circuitsg andspecifically as applicable to snap switches,.

socket switches, and various other forms.

I have illustrated a preferred embodiment of my present invention in theaccompanymg drawings, in which Fig. 1 is a front elevation of my imroved thermo-dynamically controlled kni e swvitch; Fig. 2 is anelevation looking at the right .of Fig. 1; Fig. 3 is a horizontalsection taken on the plane A-A in Fig. 1; and Fig. 4 is a diagram ofelectrical connections.

Throughout the several views of the drawings identical parts aredesignated bylike reference numerals. In the drawings, a base 1, ofsuitable insulating material, is shown carrying contact clips 2, 3,having engagement Wlth blades6, 6, which are pivoted in posts4, 5,mounted upon the base 1. An

switch closed.

insulating bar-7 connects the blades 6, 6.. A second structure composedof metal bars 8, 8, having a control handle 10 is pivoted at 12 to thebase 1. The blades 6, 6, have rilgid connection with an extension 13 tow ich is attached a coiled spring 14 fast at the other end tothe'bracket 15 on the base -1., Contact clips 16, 17, are arranged onthe base 1 to engagethe ends of the pieces 8, 8, when this structure isswung downwardly by means of the handle 10.' This engagement closes ashunt circuit, across the cllps 16, 17, (seeF'ig-d). Spring clips 11serve to hold the structure 8, 8, in the raised position, and athermostat 18 havin a wind ing 19, of suitable resistance wire, isattached to a block 20. on the base 1.

The upper end 21 of the said thermostat is bent around a rod 22,said'rod engaging with a slot in the end 23 of a bell-crank causingmovement of its free end 21, of the I rod 22, and 'of the downwardlyextending detent lever end 23 in a direction away from the insulatingbase 1. The other end of the lever 23, shown at 24, engages a projection25 on the cross piece 7, so as to hold the The operation is asfollows-to close the switch the handle 10 is pushed u which swingsthestructure 8, 8, against .t e cross bar 7, thus carrying up the blades 6,6, into engagement with their clips 2, 3, to complete the electriccircuit. At the same time the projection 25 is engaged by the end 24 ofthe lever 23, the thermostat giving, or springing, slightly to permitsuch engagement, and the switch thus locked closed against the action ofthe spring 14; a

When it is desired to open the switch, the

handle 10, is pulled down, the said handle mevingdihe structure 8,8,-away from con-- tact with the blade S l'uGt I-I'Q 6, 6, and theSpecification ofLetters Patent. Patented Feb, 21, 19,22. 1 l I manual,or other, controlling pull beingsufficient to disengage 8, 8, from theclips 11. This action forces the ends of the pieces 8, 8, into the clips16, '17, thus connecting the winding 19 in shunt to the switch load. Thethermostat is now heated, bends, moves the lever 23 as above described,and frees the end24 thereof from engagement with the projection 25,'thuspermitting the spring l l to snap the blades 6, 6, out of their clips 2,3, to open the circuit.

The desired time element, or delay, be tween the actuation of the handle10 and the opening of the circuit is obtained through the time requiredto heat to operation the thermostat 18, and this time element can ofcourse be broadly varied by altering the amount of wire in the winding19, or the amount of engagement of the lever end. 24 with the projection25.

, It will be noted that, since the thermostat circuit is shunted acrossthe load side of the switch, said circuit is dead when the switch isopened.

It is of course easily possible to apply my invention to a single poleknife switch in place of the double pole herein illustrated, in whichcasethe' thermostat circuit would be energized by being placed in serieswith the switch circuit, as set forth in my other applications referredto.

As a thermo-dynamic device tosecure opening of the" switch I have showna bimetallic thermostat, but any other suit-able type of such devicemay, of course, be emplo ed.

ithout, therefore, limiting myself to the precise embodiment hereinshown, what I claim as my invention is,-

1. In an electric knife switch having a stationary contact terminal anda pivoted, swingable, blade device adapted at one extreme positionthereof conductively to engage with said terminal, in combinationcontrolling means arranged by insulated engagement with said device toswing the latter into engagement with said terminal contact and againstthe resistance of resilient means arranged to oppose such engagement;and a thermo-dynamic device and associated mechanism. controlledthereby, adapted when thermally energized to cause the se aration ofsaid blade device from said terminal; to-

gether with an electric heater .for said thermo-dynamic device arrangedoperatively to be governed by said controlling means.

2. In an electric knlfe switch having a stationary contact terminal anda pivoted,

swingable, blade device adapted at one extreme position thereofconductively to engage with said terminal, in combination manualloperable controlling means ar ranged hy insulated engagement with saiddevice to swin the latter into engagement with said terminal contact andagainst the resistance of resilient means arranged to oppose suchengagement; and a thermo-dynamic device with associated mechanismcontrolled thereby, adapted when thermally energized to cause theseparation of said blade device from said terminal; together with anelectric heater for said thermo-dynamic device arranged operatively tobe governed by said controlling means.

3. In an electric knife switch having a stationary contact terminal anda pivoted, swingable, blade device adapted at one extreme positionthereof conductively to engage with said terminal, in combination;-controlling means arranged by insulatedengagement with said device toswing the latter into engagement with said terminal contact and againstthe resistance of resilient means arranged to oppose such engagement; adetent normally positioned to prevent separation of said ,blade devicefrom said terminal; at thermo-dynamic device operatively related to saiddetent when thermally energized to cause said separation, together withan electric heater for said thermo-dynamic device arranged operativelyto be governed by said controlling means.

4. In a knife switch for electric circuits, including a stationarycontact member and a swinging contact member adapted conductively tovengage therewith, in combination manually controllable means adapted tomove said swinging member into circuit making engagement with saidstationary member; detent means arranged normally operative to maintainsuch engagement; a thermo-dynamic device adapted, when thermallyenergized, to render said detent means inoperative; resilient mechanismarranged tending to separate said swinging member from said stationarymember; an electric heater for said thermo-dynamic device; a normallyopen circuit in shunt to the switch governed load and containing saidheater; and auxiliary switch means operably related to said manuallycontrollable meansand arranged, upon designed movement of the latter, toclose said thermo-dynamic device adapted, when thermally energized, torender said detent means inoperative; resilient mechanism arrangedtending to separate said swinging member fromsaid stationary member; anelectric heater for said thermodynamic device; and normally lnoperatlvecircuit connections operably related to said manually control-'lable'tmeans and adapted upon designed movement of the latter toenergize said heater from the switch circuit.

6, jIn aknifeswitch for electric circuits including a stationary contactmember and a co-operative swinging contact member, manual controllingmeans adapted to move said swinging member into engagement with saidstationary member, thermostatically governed means adapted to maintainsuch en- *gagement, spring mechanism adapted to separate said swingingmember from said stationary member, an electric heater for thethermostat, a normally open shunt circuit across the switch, andincluding said heater, and means, governed by a reversed movement ofsaid manual controlling means, adapted to close said shunt circuit.

' 7. In a knife switch for electric'circuits including a stationarycontact member anda co-operative swingmg contact'member, 1n

combination, manualv cdntrolling means to,

move the latter member into engagement with the former member, detentmeans adapted to retain such engagement, sprlng mechanism tending toseparate said latter member from said former member, in thermostat adated, when energized, releasingly to move sai retaining means,'anelectric heater for said thermostat, an electric circuit including saidheater, and means, controlled by a reverse movement of said manualcontrolling .means from their switch closing position,

adapted operatively to relate said last mentioned circuit to the switchcircuit, 7

8. In an 'automatically delayed-opening electric knife switch, incombination ;---a

a conductive blade structure pivoted for swinging'movement andarranged'normally to be automatically "locked in circuit-making positionat one extreme of its travel, a controlling frame for said structure,also pivoted for swinging movement and arranged by insulated positiveengagement with said structure tofmove the atter into its saidcircuit-making position, together with autof matic instrumentalitiesarranged o eratively on withdrawal of said frame 0111 said structure, tocause delayed circuit-breaking movement of said structure.

9. 1n a'knife switch for electric circuits, in combination; a stationartively to engage with said clip; an auxillary, pivoted, and manuallycontrollable frame, adapted by insulated engagement.

with said blade member, to move the latter:

' into circuit-making engagementwith said clip, a thermostaticallcontrolled detent arranged mormally to r tam said blade memher in saidcircuit-making engagement with said clip; auxiliary contacts positionedto a be connected electrically by said auxiliary frame when thelatter-is) withdrawn from engagement withsaidmember; an electric ,ratelypivoted actuatin 7 contact clip;

a pivoted blade member a apted conducheater for the thermostat; and acircuit, in shunt to the switch governed load, and including said heaterand said auxiliary contacts in series therewith; together with springmechanism adapted to se arate said blade member from. its associa edcontact clip, whereby, when said .heater is electrically energized bywithdrawal of said frame from said member, the said mechanism isautomatically rendered operative to open the switch after apredetermined time.

10. An electric knife switch structure including electrically energizedmeans for the automatic control thereof and embodying in combinationwith a swinging conductive blade andstationary circuit terminalspositioned to be contacted thereby in the circuitmaking positionthereof; an auxiliary, separately pivoted, actuating frame for saidblade a apted by positive and insulated engagement in one directiontherewith to swing said blade into its circuit-making position; aresilient detent device positioned gieldingly to retain said frame andsaid lade in said circuit-making position ofthe latter; and auxiliarystationary circuit terminals operatively related to said means andpositioned to be conductively connected by engagement of said frametherewith upon withdrawal of the latter from engagement with saidbladeand whereby said means are operatively energized.

11. An electric knife switch structure including electrically ener 'zedmeans for the automatic control thereo and embodying in combination witha swinging conductive blade and stationary circuit terminals positionedto be contacted thereby in the circuit gieldingly to retain said frameand said lade insaid circuit-making position of the latter and auxiliarystationary circult terminals operatively related to said means andpositioned to be conductively connected by enga ement of said frametherewith upon with rawal of the latter from engagement with said bladeand whereby said means are operatively energized.

12. An electric knife switch structure including electrically energizedmeans for the automatic control thereof and embodying in combinationwith a swinging conductive blade and stationary circuit terminalspositioned to be contacted thereby in the circuitmaking positionthereof; an auxiliary, separately pivoted actuating frame for said bladecomprising two side bars having conductive extensions on one side of thepivot and adapted by positive and insulated engagement with said bladeon the opposite side of said pivot and by means of an insulated handlesecured to said frame, to swing said blade into its circuit-makingposition; a resilient detent device positioned yieldingly to retain saidframe and said blade in said circuit-making position ofthe latter; andtwo auxiliary contact clips operatively related to said means and positioned each to be conductively engaged. by one of said bar extensions ofsaid frame upon withdrawal of the latter from engage-.

with said blade and whereby said means are operatively energized.

Signed at Braintree, in the county of Norfolk and Commonwealth ofMassachusetts, this 7th day of October, 1915.

MALCOLM H. BAKER.

Witnesses R. W. SMITH, SILvIo AMoRoso.

